Commutating apparatus



y 1965 F. R. QUINN COMMUTATING APPARATUS Filed Dec. 3, 1962 FIG.

FIG.8

m m M ATTORNEY United States Patent 3,182,217 COMMUTATING APPARATUS Frederic R. Quinn, Red Hook, N.Y., assignor to Zyrotron Industries, Inc., Red Hook, N.Y. Filed Dec. 3, 1962, Ser. No. 241,594 1 Claim. (Cl. 310-235) This invention relates to improvements in apparatus with commutators and brushes and the like and to the process of making them. While the invention is particularly advantageous as applied to commutating motors for airborne equipment, it is also applicable more broadly, including slip-ring devices, telephone step switches, decade type terminal panels and any other device in which a set of conductive terminals are arrayed on a supporting insulator, with the exposed surfaces of the terminals flush with the surface of the insulating support on one side, the combination offering a smooth surface for a brush to slide on that surface to make selective contact with a desired terminal or group of terminals.

An object of the invention is to provide substantially lighter and more powerful commutating apparatus for rotating electrical equipment and the like.

Another object of the invention is to provide an improved commutator for such apparatus.

A still further object of the invention is to provide an improved process for making commutators very accurately and conveniently whereby tolerances may be reduced to a minimum with safety, spoilage reduced, production speeded up, and manufacturing costs reduced substantially.

Other objects and advantages of the invention will be evident from the following description taken in conjunction with the accompanying drawing which constitutes a part of this specification and in which:

FIG. 1 is a perspective view of the initial form of a commutator as it comes out of the foundry cope, or powder press, or broaching machine, and represents the first stage in the manufacture of the improved commutator.

FIG. 2 shows a cutaway view of the product in the next stage of its manufacture-as it comes out of the plastic mold or press, with the shaft molded in.

FIG. 3 shows the finished commutator as it comes out of the machine shop and assembled with brushes and the rest of the apparatus to which it belongs.

FIG. 4 illustrates, partially in section, the preferred simple equipment and process for the molding of the product of FIG. 1 to produce the product shown in FIG. 2.

FIG. 5 shows in a cutaway perspective the first stage of a slip-ring device according to the present invention, and FIG. 6 the final stage ready for mounting with the rest of the apparatus of which it constitutes an essential working part.

FIG. 7 and FIG. 8 similarly illustrate the first and last stages of a flat panel with flush terminals, manufactured in accordance with the present invention.

Referring to FIG. 1 in greater detail, part 10, the initial form of the commutator, will be seen as a cylindrical array of commutator segments 11, accurately spaced with slots 12, and securely held together by an outer cylindrical web or shell 13, integral with the segments. The whole thing looks somewhat like a motor stator core in marked contrast to the conventional commutator manufacture in which in the initial stage each commutator segment is punched out individually, for later assembly together with appropriate insulating strips, such a mica, between each pair of adjoining segments.

The product of FIG. 1 can be made either by casting, or by powder press metallurgy, or by broaching. Conventionally the commutator segments are made of copper, and that metal may be used here also.

3,182,217 Patented May 4, 1965 ICE In the second stage of the manufacture of the commutator, the commutator of FIG. 1 is impregnated with an insulating plastic or resin, preferably with the shaft in place, as illustrated in FIG. 4, where the commutator 10 (shown in section) will be seen as set, with its axis vertical, in a shallow recessed tray 14 (also shown in section) with the shaft 15 set in the center. Non-conducting liquid plastic, such as epoxy resin, is poured inside the commutator shell to fill it, including all free spaces such as the slots and any recesses in them. After the resin sets, the commutator and shaft assembly of FIG. 4 looks as shown in the cutaway perspective of FIG. 2.

In the above process, the commutator segments 11 are so firmly imbedded in and held by the resin 16 that the shell 13 is no longer needed for this purpose. Consequently, as the next operation, this shell is turned down on a lathe, leaving the commutator in its finished form as shown in FIG. 3, where the commutator segments will be seen as insulated from each other by the harder plastic and offering a smooth cylindrical outer surface for contact with two brushes 18. When the commutator is being turned down to shave off the shell, a flange or shoulder 17 is left at one end for the conventional lead connections.

An additional advantage of the plastic insulation instead of the conventional mica between the commutator segments is that the plastic, being of about the same hardness as the metal of the commutator, will wear evenly with the segments, and therefore will not cause brush chatter that a slightly projecting mica spacer will.

In FIG. 5, part 19 is the initial form of a set of three conductive metal slip-rings 20, 21 and 22, accurately spaced and securely held together by shell 23 integral with them. This part 19 may be cast, or it may be formed by grooving a hollow cylinder on a lathe.

Leads 20a, 21a, and 22a may now be connected to the slip-rings as shown, and then part 19 is set up like part 10 in FIG. 4, preferably with the shaft also in place, to fill it with the selected plastic liquid. After the plastic sets, the product is turned down on a lathe to remove the shell 23, leaving the product in the form shown in FIG. 6 ready for assembly with the apparatus of which it forms a working part-the three rings insulated from each other, and the metal and the plastic providing a smooth cylindrical surface for a brush or brushes for contact between the apparatus circuit and an external circuit.

In the fragment of a flat switching panel shown in FIG. 7, parts 24 and 25 illustrate conductive terminals, 24 as an extended bar and 25 as a spot terminal. These two and other possible shapes and arrangements of terminals are accurately spaced and securely held together by a shell or web 26, with a rim 27 that goes around all four edges of the shell or web. This product also may be cast or produced by any other means. This then is filled with the chosen plastic in moldable form and when the plastic sets, the shell or web 26 is removed, as for instance on a milling machine, leaving behind the finished panel with a smooth as shown in FIG. 8, suitable for brush contacts and ready for connection into the circuit of which it constitutes an essential part.

The invention having been fully disclosed as to its use, structure, composition, organization and process with the help of a preferred embodiment and some variations thereof, still other modifications within the spirit of the invention will occur to those skilled in the art, and I intend to include all such modifications in the appended claim limited only by the prior art.

What is claimed is:

A commutator device comprising:

(a) an initial form comprising an annular ring formed of an electrical conducting material,

(b) said ring having formed therein a plurality of key shaped slots to define commutator Segments therebetween whereby said segments are interconnected by an arcuate Web portion of said ring, said slots being radially disposed and each of said slots having its narrow end opening to the inner periphery of said ring, 5

(0) each of said slots terminating at its other end in a recessed portion having a Width which is less than that of the wide end of said slot and said recess being in communication with said slot,

(d) an electrically insulating plastic material imbedded in said slots and respective'recesses thereof whereby the ratio of the exposed area of the commutator segments and insulating material therebetween can 15 Reterences Cited by the Examiner UNITED STATES PATENTS 7/30 Apple 310235 5/44 Armel 310-235 V 7/53 Marsal 310-236 X 2/54 Johnson 310265 FOREIGN PATENTS 10/50 France.

MILTON O. HIRSHFIELD, Primary Examiner. 

